While the most high-profile security vulnerability of late was almost certainly the WMF hole recently patched by Microsoft, in terms of actual numbers of infections it was barely a blip on the radar. According to the anti-virus company F-Secure, one of the most populous and dangerous infections today is not some sophisticated bit of code exploiting a new and exotic security hole, but an old-school e-mail worm written in Visual Basic that spreads by tempting users with free pornography.